The terms Left and Right were coined in 1789 to describe seating arrangements for the National Assembly during the early stages of the French Revolution. Those seated to the podium’s right wanted to preserve parts of the past; those on the left hoped, in the name of progress, to invent a new future. But the maneuverings of politics soon muddied the initial transparency of these terms into an enduring illegibility. The ideas of the bloody minded right-wing reactionary Joseph de Maistre, the intellectual arch-enemy of the Revolution, for instance, became an inspiration for the early socialists—and so it has gone ever since.

The flamboyant French litterateur Bernard-Henri Lévy, widely known in Paris as BHL, acknowledges the problem. In his new book, he writes that “the famous split between Left and Right that has structured French politics . . . has become harder and harder to believe in.” That is because, to his dismay, much of the Left, cuckolded by history, no longer believes in progress or modernity. He describes the contemporary Left, with its signature scowl of anti-Americanism, anti-Semitism, and anti-liberalism, as “that great backward falling corpse which the worms have already started to chew.”

Despite his disdain for much of the current Left, and despite the fact that many of those closest to his point of view in France endorsed the presidential candidacy of the “right-wing” flag bearer Nicholas Sarkozy, a personal friend, Lévy refused to abandon the Socialist ticket. His dilemma, he told Sarkozy, was that no matter how much he liked, respected, and even agreed with the French president, he couldn’t support him because “the Left is my family.” Lévy’s new book is an effort—part memoir, part essay, part polemic—to explain the nature of those family ties.

“And does my insistence, on sticking with the Left that has done everything to empty itself of its substance mean I’m clinging to yesterday . . . to nostalgia? . . . Yes, maybe,” Lévy writes. “But not only.” Lévy’s “not only” refers to the images he treasures of his father in the uniform of the Spanish Republicans who fought Franco; of the great resistance hero Jean Moulin; of the brave socialist Prime Minister of the 1930s, Leon Blum. He acknowledges that “images are not enough” and describes the events that shaped his loyalties and those of his parents. These include the Dreyfus Affair, Vichy France, and the Algerian War, as well as being a young man during the uprisings of May 1968. He wonders if he is worthy of his illustrious ancestors, such as the “young left-wing captains in Portugal 1975 bringing down the Salazar dictatorship.” But here again, he backtracks and adds, “It is true that none of these events can completely justify the clear division of Right and Left.” He recognizes that some on the Right supported Dreyfus and the events of May ’68, while “many socialists . . . pacifists and sometimes Communists” took part in Vichy’s crimes. “These events,” he concludes, “are split by the same dividing line that they purport to draw.”

Some American readers will find themselves exasperated by Lévy’s very French form of discursive, emotional writing, which lacks the concision and specificity of the best English-language essays. BHL criticizes Sarkozy for supposedly writing off the Arab and Islamic rioters of the banlieues who need to be incorporated into France, for example. But his moralizing leaves no room to discuss the rigid terms of France’s statist economy, which makes it almost impossible to create jobs for the unemployed beurs, who have plenty of time to fester on welfare. And some of his concerns are far more salient in a European context than in an American one. Most Americans don’t realize that much of Tony Blair’s cabinet in England consisted of former far-leftists; or that Massimo D’Alema, Italy’s prime minister at the end of the 1990s, was formerly a communist; or that Lionel Jospin, French Prime Minister from 1997 to 2002, had earlier been a Trotskyist for two decades.

But, argues BHL, whatever the considerable failings of those older iterations of Leftism, until the fall of the Soviet Union the Left still had something like a positive agenda. Since then, Leftists—reduced to “the joint ownership of resentment”—have increasingly turned against their parentage, the Enlightenment. The Left now defines itself so closely by its hatred of America and Israel that anti-globalization activists even draw on counter-Enlightenment figures—such as the philo-Nazi political theorist Carl Schmitt—to create what BHL calls “a right-wing left.”

The Left’s once proud universalism has devolved into an ethnic particularism, of the sort that once found its home in the fever swamps of the far Right. “We are in a world in which, on the one hand, we have the United States, its English poodle, its Israeli lackey—a three-headed gorgon that commits all the sins in the world—and, on the other side, all those who, no matter what their crimes, their ideology, their treatment of their own minorities, their internal policies, their anti-Semitism and their racism, their disdain for women and homosexuals, their lack of press freedom and of any freedom whatsoever, are challenging the former” and are thus to be defended, Lévy laments. Here he refers, among other examples, to the case of British Leftist playwright Harold Pinter who became, during the Bosnian slaughter of the 1990s, an ardent defender of Slobodan Milošević.

Lévy has fought the good fight. His courageous book Who Killed Danny Pearl, based on his extensive travels in Pakistan, unflinchingly described the radical evil of our time. But under the spell of a hopelessly confused nomenclature, BHL, sticking to his anti-Sarkozy guns, concludes with a call for what he terms “melancholy liberalism.” The phrase may sound odd to American ears, but its content is quite familiar. It’s another name for the disillusioned liberalism of 1950s America, with its strong sense of nuance, irony, and complexity. It’s a chastened liberalism worthy of admiration. But after following BHL’s stylish twists and turns in describing the creation of a “right-wing left,” the reader is bound to ask at least two questions. First, when is it time to leave a dysfunctional family? And second, is it not time to free ourselves, as much as possible, from a hopelessly outdated and unavoidably misleading set of political categories?

Fred Siegel is a contributing editor of City Journal and a professor of history at the Cooper Union for Science and Art.